The use of agonist of GnRH (aGnRH) trigger to avoid ovarian hyperstimulation syndrome is nowadays widely used. The action of the aGnRH in the hypophysis triggers an LH and FSH surge, which mimicks the natural surge that occurs in the middle of a natural cycle, and thus being able to elicit the ovulation. However, in some patients the aGnRH trigger ends in a poor oocyte recuperation, and that has led some physicians to measure the LH surge after the aGnRH trigger to check its effectiveness.

Even though there is still some discrepancy about the exact cut-off value for a proper LH surge 12h after the aGnRH trigger, most of the published papers report the value of 15UI/L as an adequate threshold under which the results of the pick-up are suboptimal. Other authors even report a value of 52UI/L to predict a decrease in oocyte retrieval and maturity rate and a value of 15UI/L to predict a dramatic decrease in the results.

Some of the abovementioned studies report that the basal LH value or the LH value on the day of the trigger could also be predictive of suboptimal responses. Additionally, some authors have tried to "rescue" the suboptimal patients with a retrigger of hCG, or they have compared those suboptimal responders with patients triggered with both aGnRH and low doses of hCG. In both cases the addition of hCG seems to improve the results.

Most of the scientific bibliography available so far is based on infertile patients undergoing IVF treatments, while in some papers both IVF patients and egg donors have been analyzed. The current study involves exclusively oocyte donation cycles, where the final aim is to identify donors at a high risk of a suboptimal response, and to potentially improve results by potentially adding low doses of hCG (1000 UI).

Inclusion Criteria:

• Oocyte donors included in the oocyte donation program of Clinica EUGIN that have been triggered with GnRH agonists.
• Any cycle of oocyte donation from the program of Clinica EUGIN, regardless of the type and dose of gonadotropin used for stimulation.

Exclusion Criteria:

- None.

Oocyte donors included in the oocyte donation program of Clinica EUGIN